Domestics and 2 way switching

[SUNRAY]

"Mornin Sunray. Do us a favour and sort out a switch along the road."

"More 5h1t?"

"Dunno, he says he's changed a 3 gang all 2 way but 5 wires except he says only 4 used. I sent Mark but he says it's something wierd and you have to go."

"Interesting."

I grabbed a small toolkit and a 3g switch (just incase) and made the 20 minute walk, expecting to find 5 cables, like 3x 3C&E and 2x T&E.
Being shown into the large open plan lounge/diner/kitchen some 40ft x 15ft or so with the only soft items being a leather 5 seater corner sofa affair and the wallpaper on one end wall. I was demonstrated a fully functional 3C switch by the kitchen area door from the hall and another by the quad fold patio door. At that point I assumed it had been sorted and mentally I was halfway home.

With the power on I didn't expect to find this by the other hall door:

Nor did I expect to be told this switch has the same functionality as the other 2.
Nor did I expect to be told the black on the right was tucked behind the 3 sheathes.

"I did get it so the middle switch also controlled the other 2."

LED screwdriver soon found the left red was showing as live and from there the 3 at the bottom showed 240V without any variation as other switches altered.

I have sorted it but what would others do next?

 

[sparkwright]

I would look behind the other 2 switches, partly to see if any are any intermediates, partly to see if all three switches were intended to be 2-gang only instead of 3-gang, and partly to see what the hell is going on.

Will we eventually get to see the other two switches before the solution is revealed?

That's going to be my guess what the problem was - it was intended that there should be three lights, each light controlled by two 2-way switches, using three 2-gang switches - and someone has tried to make it work with 3-gang switches.

 

[Adam_151]

Dunno, he says he's changed a 3 gang all 2 way but 5 wires except he says only 4 used.
...
I was demonstrated a fully functional 3C switch by the kitchen area door from the hall and another by the quad fold patio door. At that point I assumed it had been sorted and mentally I was halfway home.

With the power on I didn't expect to find this by the other hall door:

.....
Nor did I expect to be told this switch has the same functionality as the other 2.
.....

LED screwdriver soon found the left red was showing as live and from there the 3 at the bottom showed 240V without any variation as other switches altered.

So the other two switches have their desired functionality with everything open at this point, only four conductors in use, one shows as being live and it reads 240v to each of the three others as if there is some sort of path back to neutral through a load.... Well I'm guessing then that its going to be something like theres a live feed comming in, and three switch wires out to changeover relays acting as one end of the two way arrangement. Which are probably not installed in a suitable manner for fixed installations because they were likely soldered in a haphazard way and glued inside a tobbaco tin in the far end of the loft circa 1982 by some model railway enthusist. There will probably be some hieroglyphics on how he has wired it along with a good few stubbed out fag ends

 

[SUNRAY]

I would look behind the other 2 switches, partly to see if any are any intermediates, partly to see if all three switches were intended to be 2-gang only instead of 3-gang, and partly to see what the hell is going on.

Will we eventually get to see the other two switches before the solution is revealed?

That's going to be my guess what the problem was - it was intended that there should be three lights, each light controlled by two 2-way switches, using three 2-gang switches - and someone has tried to make it work with 3-gang switches.

I looked at one switch and it had 2x T&E, one wire connected as a common to all 3 gangs.
This worked, but I did tidy the exposed copper:

The yellow links were retained from the original switch and matched those in the other switch.

So the other two switches have their desired functionality with everything open at this point, only four conductors in use, one shows as being live and it reads 240v to each of the three others as if there is some sort of path back to neutral through a load.... Well I'm guessing then that its going to be something like theres a live feed comming in, and three switch wires out to changeover relays acting as one end of the two way arrangement. Which are probably not installed in a suitable manner for fixed installations because they were likely soldered in a haphazard way and glued inside a tobbaco tin in the far end of the loft circa 1982 by some model railway enthusist. There will probably be some hieroglyphics on how he has wired it along with a good few stubbed out fag ends

Close enough. It is a CU containing DIN rail mounted low profile relays, Way up high in one of the kitchen wall cupboards. I didn't investigate but I suspect the relay contacts were wired like 2 way switching. What I could see of the wiring through the front open slot and clear flap it looked a bit 'thrown in' but I don't think any worse than many CU's. It's a wide plastic unit about half full which I suspect had been their mains CU.